Пошаговое объяснение:
3/7х - 13/15 = 3 1/3 : 1 9/16
3/7х - 13/15 = 10/3 : 25/16
3/7х - 13/15 = 10/3 * 16/25
3/7х - 13/15 = 2/3 * 16/5
3/7х - 13/15 = 32/15
3/7х = 32/15 + 13/15
3/7х = 45/15
3/7х = 3
х = 3 : 3/7
х = 3 * 7/3
х = 21/3
х = 7
